Selective thermal radiators

Abstract

An improved thermal radiator uses host materials having high internal reflection and scattering co-efficients for improved effectiveness. Selective thermal radiators are used for frequency conversion of incident radiation through the Welsbach effect. A Welsbach material screen is used to convert incident IR radiation into visible radiation, permitting visual observation of IR radiation and facilitating control and monitoring of IR equipment. Welsbach material is also used as a dynamic IR target which converts incident visible radiation into a high resolution IR source pattern. Welsbach material is also employed as a temperature stable material for converting solar radiation into heat.

What is claimed is: 
     
       1. A method for producing an image of applied infrared radiation, comprising the steps of: (i) providing a means for converting incident infrared radiation within an infrared wavelength interval into visible radiation within a visible wavelength interval, said means comprising a screen means for efficiently absorbing said incident infrared radiation, said screen means further comprising means for producing high internal scattering of said absorbed incident infrared radiation within said screen means, and means responsive to said absorbed infrared radiation for producing a visible light image corresponding to the intensity of said infrared radiation, said screen means comprising a screen formed from a selective radiator material less than 300 microns in thickness and having the properties of high absorption of said incident infrared radiation withn said infrared wavelength interval, high internal reflection of said absorbed infrared radiation, high emissivity of radiation within said visible wavelength interval and low emissivity at intermediate wavelengths;   (ii) illuminating said screen with radiation within said infrared wavelength interval; and   (iii) radiating light from said screen in response to said illumination to provide a visible light image corresponding to the intensity of the illumination radiation.   
     
     
       2. A method for producing desired patterns of infrared radiation, comprising the steps of: (i) providing a means for converting patterns of incident visible radiation having corresponding spatial intensity distributions into infrared radiation patterns having spatial intensity distributions corresponding to said spatial intensity distributions of said visible radiation patterns, said means comprising a screen less than 300 microns in thickness of selective thermal radiator material having high absorption at visible wavelengths and high emissivity at infrared wavelengths;   (ii) illuminating said screen with selected patterns of visible radiation having corresponding spatial intensity distributions corresponding to said desired patterns; and   (iii) radiating infrared light from said screen in response to said illumination to produce said desired patterns of infrared radiation.   
     
     
       3. A system for producing a visible image of the spatial intensity distribution of an infrared beam generated by an infrared laser, comprising: an infrared laser for producing an infrared light beam having a cross-sectional spatial intensity distribution;   a target screen disposed for illumination by said infrared light beam, said screen comprising means for receiving said infrared light beam and converting said received infrared radiation into a visible image having a visible spatial intensity distribution corresponding to said intensity distribution of said infrared light beam;   said target screen comprising a thin screen less than 300 microns in thickness and formed from a selective radiator material comprising a base material comprising means for efficiently absorbing said incident infrared radiation and means for providing high internal reflection of said absorbed infrared radiation, and a dopant material responsive to said absorbed radiation for emitting radiation within a visible wavelength interval, said selective thermal radiator material having low emissivity at intermediate wavelengths.   
     
     
       4. The system of claim 3 wherein said base material is selected from the group consisting of zirconium oxide and thorium oxide, and said dopant comprises cerium oxide. 
     
     
       5. The system of claim 3 wherein said infrared laser is a carbon dioxide laser. 
     
     
       6. A system for producing a visible image of the spatial intensity distribution of an infrared beam generated by an infrared laser, comprising: an infrared laser for generating an infrared light beam having a selected cross-sectional spatial intensity distribution forming an infrared image;   a target screen disposed for illumination by said infrared light beam, said screen comprising means for converting said infrared light beam into a visible image having said spatial intensity distribution, said means comprising a layer of selective thermal radiator material less than 300 microns thick, said material comprising a base material selected from the group consisting of zirconium oxide and thorium oxide, and a dopant material comprising cerium oxide.   
     
     
       7. A system for providing an infrared image having a selected spatial intensity distribution, comprising: a visible laser for providing a visible light beam having a selected cross-sectional spatial intensity distribution;   a target screen disposed for illumination by said visible light beam, said screen comprising means for converting said incident visible light beam into an infrared image having a spatial intensity distribution corresponding to said visible light beam distribution, said means comprising a layer of selective thermal radiator material less than 300 microns thick, said material comprising a base material selected from the group consisting of zirconium oxide and thorium oxide, and a dopant material comprising cerium oxide.   
     
     
       8. The system of claim 7 wherein said visible laser comprises a HeNe laser. 
     
     
       9. The system of claim 7 further comprising a means responsive to said emitted infrared image for observing said image. 
     
     
       10. The system of claim 9 wherein said means for observing said infrared image comprises a forward-looking infrared radar. 
     
     
       11. The method of claim 1 wherein said illuminating step compries applying a pattern of said infrared radiation and said radiating step comprises producing an image of said pattern. 
     
     
       12. The method of claim 11 wherein said pattern comprises a beam of infrared radiation. 
     
     
       13. The method of claim 12 wherein said beam is focused. 
     
     
       14. The method of claim 13 wherein said image comprises a profile of said focused beam. 
     
     
       15. The method of claim 1 wherein said illuminating step comprises applying laser radiation. 
     
     
       16. The method of claim 1 wherein said illuminating step comprises the sole means for heating said screen. 
     
     
       17. The method of claim 2 wherein said patterns of visible radiation comprises images. 
     
     
       18. The method of claim 2 wherein said illuminating step comprises applying laser radiation. 
     
     
       19. The method of claim 2 wherein said illuminating step comprises the sole means for heating said target.